Improved mode of



ii lnimi fitatrt patent tililirr.

WILLIAM THORPE, OF LOUIS, MISSOURI.

Letters Patent No. 9.543%, dated October 5, 1869.

IMPROVED MODE OI APPLYING- INKS OF DIFFERENT CHARACTERS, SO AS TO PRINT SAFETY, REVENUE, AND OTHER STAMPS.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may concern:

Be it known that I, \VILL1AM THOR-PE, of the city of St. Louis, in the county of St. Louis, and State of Missouri, have invented certain new and useful Improvements in the Manufacture of Stamps for the Use of the Internal-Revemue Bureau, the Post-Ofiice Department, or any department, ofiice, orperson, so as to prevent their reuse, and to prevent much as possible the counterfeiting of the same.

The nature of my invention consists in the printing each of such stamps with two kinds of ink of different colors, and so diii'erent in their chemical composition that a solution of any acid will destroy the one, while the other will be likewise destroyed by the action of a solution of any alkali, the object being to prevent the removal of the cancellation-marks from such stamps after they have been once used and cancelled.

And further, in so disposing the ink of the ground color, and that with which the letters, figures, and vignette or other devices are printed, as to render it impossible" for the marks of cancellation to touch one kind of ink without touching the other, and' at the same time to render it extremely difficult, if not impossible, to counterfeit such stamps.

To enable others skilled in the art to use my invention, I will proceed to describe the same.

I claim no novelty as to size, form, vignette, or mechanical means of imprinting the colors. or devices upon the stamps.

One of my inks, which I will call the green ink, -I make of about fifteen parts of verdigris, two parts of ultramariue, one-half part of chrome-yellow, with boiled linseed-oil and flake-white in suflicient quantities to give it proper consistence or body.

The other, which may be called the red ink, is composed of about fifteen parts of litmus-red and one part of carmine-lake, together with boiled linseed-oil and flake-white in quantities suflicient to give the ink proper consistence. or body.

These colors may be varied, as may be desired, but there should always be a decided contrast between the two inks used in printing a stamp, as to color, and one of them should be as sensitive as possible to the action of the acids, while the other should be sensitive, and as much so as possible, to the action of the alkalies.

The ink which is sensitive to the action of the acids should be so in a greater degree, if practicable, than ordinary writing-ink, so that when cancellation-marks made with writing-ink are removed by the use of an acid, such ink-color will certainly be removed at the same time; and, on the other hand, the ink which is sensitive to the action of the alkalies should be more sensitive to their action than printers ink, so that when the stamp has been cancelled with printers or other similar ink, and such ink has been removed by the use of an alkali, some part of the ink of the stamp will certainly be removed at the same time, and thus the stamp will'inevitably and effectually be destroyed. Reference here is had to the two modes prescribed by law for the cancellation of revenue and postagestamps; one by the use ofa pen'and writing-ink, the other by the hand or other stamp and printer-s ink.

The letters, figures and vignette, and other devices,

should be printed upon and after theground color has been imprinted, and they should be so disposed-aml arranged upon the ground color of the stamp as to leave no large spaces not covered by them, so that the ink from the cancelling-instrument will invariably touch and cover over some portion of inks of the stamp.

The difiiculty of extracting the ink usedin-cancel-- ling-might be much increased by the use of paper for the stamp which has been only partially sized, so that theink' used in cancelling would penetrate it more deeply. This means might increase the security of effectual cancellation.

I have thus far mainly devoted my attention to describing in what manner, by my invention, the destruction of the marks of cancellation and the reuse of the stamp may be prevented. But another principal objeot of my invention is to prevent the counterfeiting of stamps.

'Four diiferent modes of counterthiting stamps have been resorted to with more or less success:

First, by the transfer-process, which consists in softening, by a solution of alkali, the ink upon the stamp, from which an impression is then transferred to a steel plate. The form of the stamp is then engraved upon the plate, after which any number of stamps may be printed from it with great accuracy.

Second, by lithography, which is similar to the above, stones being used instead of steel plates.

Third, by photography.

Fourth, by tracing, which is an old and well-known method, and consists in tracing out the lines of the stamp upon a plate first, and then engraving the same, after which the stamp is printed. 1

Now, for instance, the first or ground color will be assumed to be the one most sensitive to the action of the acids, and the engravings upon it to have been made of lathe-work with a suitable design. Then the other color should be the one most sensitive to the action of alkalies, and the engravings upon it should consist 'of a vignette, letters, figures, with anyother desired devices, and a border for the stamp. Then, when an attempt is made to transfer the stamp, the ink which is most sensitive to the alkalies will be destroyed, and pass off into the solution used before the other hecomes sutficiently softened to be transferred, and thus the attempt wilhbe defeated.

The use of two difi'erent colors in printing the stamps, and they imprinted at different times and by two distinct operations, one over and upon the other, would necessarily result in such a commingling of tints and colors as to render counterfeiting by means of photography utterly impracticable.

The use otlathe-work, 850., will render the counterfeiting by tracing an impossibility, for no hand, however skilled and steady, could follow the innumerable lines, curves, and angles of the lathe-work.

The fact of the colors being printed over and through each other will greatly increase the difficulty of counterfeiting by any means whatever.

As fnrthernieans of preventing counterfeiting, the

stamps should be engraved and printed in the best and most finished manner. The lathe-work should be open, so as not to blur, and a vignette should be used, as it hasbeen found, by experience, to greatly increase the difliculty of counterfeiting. The letters and figures should be as light and open as possible, so that the tint of the lathe-work beneath theinmay be plainly seen. There should be no heavy work on thestamp, unless it be in the margin orborder.

1n the use of my invention, I do not restrict myself to the two inks described, but will use any two inks now in use, or that hereafter may be made, having the properties and qualities requisite to produce, in combination with each other, the results described in the manner set forth. Nor do I restrict myself to any of the known mechanical means of communicating the inks and colors to the paper, and I use herein the terms printing and engraving interchangeably, to signify impressing the colors or inks upon the stamp.

\Vhat I claim as new, and desire ters Patent, is-

1. In the printing of stamps for internal-revenue,

to secure by Let- 'that one oi the inks shall have a sutl'icient postal, and other purposes, the combination of the two inks'described, or of any other two inks, of whatever ingredients and proportions thereof composed, provided affinity for the acids, while the other shall have a like aflinity for the alkalies, and the two shall produce substantially the results described, substantially in the manner described.

2. The using of any two inks of decidedly diii'erent colors and of materially different chemical aiiinitic's, one for the acids and the other for the alkalies, so that while one of them will be destroyed by the action of the acids, the other will be destroyed by the action of the alkalies, and the imprinting the stamp with one ink, and by printing the letters, vignette, or other devices with the other ink over and upon the first impression, so as to commingle the tints and colors of the two upon the face of the stamp, for the purpose of preventing the removal of the ink used in cancelling, without also destroying at least one of the inks used in printing the stamp, and as a means of increasing the difiiculties of counterfeiting the same, when used and done substam tially in the manner described.

3. In combination with the described mode of inking or coloring the paper of the stamp, paper sized with any material which is delicately sensitive to the action of chemical solvents, so that an attempt to remove the ink used in cancelling, by the use of either an acid or an alkali, will result in the destruction of the sizing, as well as one of the inks of the engraving, substantially as set forth.

4. The described stamp forinternal-revenue, postal, and other purposes, made substantially as described and set forth, as a new article of manufiicture.

WM. THORPE.

Witnesses:

A. M. STOUT, S. A. Pnnon.

the ground color upon another operation im- 

